I am using my 8700c with telenav and a gsat (offered by cingular) BT GPS and it works great. The telenav support line sucks and it took quite some time to get someone that could set up my account without a credit card (cingular bills me monthly) but finally got it worked out and it's great.

When you say works great tell me more. Can you enter a start and end point, and does it react well if you go off course. Does it give audible directions too?

How do you get Cingular to bill you? Is that something they are selling?